Adolescent rats are more prone to binge eating behavior: a study of age and obesity as risk factors

Binge eating (BE) is characterized by repeated, intermittent over-consumption of food in a brief period of time. This study aims to advance the understanding of potential risk factors for BE such as obesity, overeating and adolescence as an age group. We used the Otsuka Long Evans Tokushima Fatty (OLETF) rat, a genetic overeating-induced obesity model with increased preferences for sweet and fat. Adolescent and adult rats from both strains (OLETF and the lean control strain, Long Evans Tokushima Otsuka [LETO]) received limited access to a palatable liquid diet (Ensure vanilla) for three weeks. Water and chow were available throughout the study, but access to Ensure was limited to two hours, three times a week (3TW group) or every work day (5TW group). As expected, OLETF rats consumed more Ensure and were more BE-prone (BEP) than LETO rats at both ages. Adolescent rats showed a significantly larger binge size as demonstrated by a greater increase in Ensure intake, compared to adults. Furthermore, while the adults reduced their chow intake, compensating for increased Ensure intake, the adolescents increased their chow intake too. Finally, the adolescent rats showed binge like behavior earlier in the study and they tended to be BEP more than the adults. Our findings in rats suggest that adolescents and in particular obese adolescents are at risk for BE, and BE can lead to overweight, thus providing the basis for examination of biological mechanisms of this process in animal models.